Optical limiting behavior of ring substituted zinc, indium and gallium phthalocyanines in the presence of quantum dots
- Authors: Britton, Jonathan , Litwinski, Christian , Durmus, Mahmut , Chauke, Vongani , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247122 , vital:51548 , xlink:href="https://doi.org/10.1142/S1088424611004142"
- Description: This paper presents the study of the effects of CdTe-TGA quantum dots (QDs) on optical limiting ability of different phthalocyanine (Pc) complexes (1–10) containing Zn, Ga, In central metals and substituted with benzyloxyphenoxy, phenoxy, tert-butylphenoxy and amino groups. The optical limiting parameters of Pcs were higher for tert-butylphenoxy when compared to benzyloxyphenoxy and phenoxy substituents, in DMSO. Non-peripheral substitution decreased the optical limiting parameters. Third-order susceptibility (Im[χ(3)]/α) values of Pcs in the absence and presence of CdTe QDs were in the 10-12 to 10-10 esu.cm range. Hyperpolarizabilities (γ) ranged from 10-31 to 10-29 esu L for Pc alone or in mixture with QDs. There is a general improvement in optical limiting ability of Pc complexes in the presence of CdTe TGA QDs. Due to these promising results, future work can be implemented for the creation of Pc:QD thin films, which would then be examined to ensure that their optical limiting ability is still acceptable.
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- Date Issued: 2011
Optimal template removal from molecularly imprinted polymers by pressurized hot water extraction
- Authors: Batlokwa, Bareki Shima , Mokgadi, Janes , Nyokong, Tebello , Torto, Nelson
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247813 , vital:51620 , xlink:href="https://doi.org/10.1007/s10337-010-1884-3"
- Description: An optimal extraction method for the removal of templates from molecularly imprinted polymers (MIPs) is presented. The extraction method is based on pressurized hot water extraction (PHWE). PHWE was evaluated by application to three distinctly colored MIPs for chlorophyll (green), quercetin (yellow) and phthalocynine (dark blue) with subsequent monitoring of template removal and template bleeding by an ultraviolet spectrophotometer. The templates were washed-off and the extraction efficiency (EE) was compared to that of soxhlet and ultrasonic extraction methods. PHWE employed hot water at an optimal temperature of 220 °C, pressure of 50 bars and flow rate of 2 mL min−1 to thoroughly wash-off the respective templates from their MIPs. The EE evaluated for PHWE was over 99.6% for all the MIPs with no subsequent or minimal template bleeding (more than 0.01%). The washing procedure was simple and relatively fast as it was achieved in 70 min at the most. At 95% confidence level (n = 3), soxhlet and ultrasonic recorded EE that was not significantly different (more than 94.5% in all cases) from that of PHWE (less than 99.6% in all cases). Soxhlet and ultrasonic had washing procedures that were slower (over 18 h) and employed large quantities (400 mL) of organic solvents modified with acids. The percentage relative standard deviations (%RSD) for the EE and recovery results were less than 2.3% in all cases indicating the high reproducibility of the method. Overall, the three methods performed comparably in extracting templates. PHWE seems to be the method of choice as it employed water which poses no environmental threat.
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- Date Issued: 2011
Optimizing the electrocatalytic activity of surface confined Co macrocyclics for the electrooxidation of thiocyanate at pH 4
- Authors: Tshangana, Charmaine , Pavez, Jorge , Gulppi, Miguel A , De Mattos, Ivanildo Luiz , Arratia-Perez, Ramiro , Linares-Flores, Cristian , Paez, Maritza , Nyokong, Tebello , Zagal, Jos H
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247726 , vital:51612 , xlink:href="https://doi.org/10.1002/elan.201000599"
- Description: We have studied the trends in catalytic activity of several Co macrocyclics confined on the surface graphite electrodes for the oxidation of thiocyanate. A plot of log i (at constant E) versus the formal potential of the catalyst gives a volcano correlation, indicating that the Co(II/I) redox potential needs to be tuned, in order to achieve maximum reactivity. Graphite electrodes modified with Co phthalocyanine at pH 4 exhibit linear amperometric response for thiocyanate concentration in the range 10−7 and 10−3 M. Theoretical calculations show that electrocatalytic activity (as log i at constant E) plotted versus the energy of the LUMO of the Co complex also gives a volcano correlation.
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- Date Issued: 2011
Organizational commitment, age and gender effects on organizational citizenship behaviour of university employees
- Authors: Khayundi, Daniel Asiachi
- Date: 2011
- Subjects: Organizational behavior -- South Africa , Organizational effectiveness -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/25755 , vital:64476
- Description: Organizational citizenship behaviour is one of the important factors that enhance organizational effectiveness. The main purpose of this study was to explore the impact of Organizational commitment on Organizational Citizenship Behaviour (OCB). In this study, age and gender effects on OCB of tertiary institution employees were also examined. The data was collected from 68 academic and administration staff from the University of Fort Hare, Alice campus through questionnaires. The results show that 68 respondents are of the view that organizational commitment impacts positively in enhancing the organizational citizenship behaviour of the employees. The findings also reveal that age and gender play no role in the practice of employees OCB. Management can increase the levels of OCB in their employees by recognizing employees who engage themselves in such behaviour. Implications that can help management in the University of Fort Hare, Alice campus in augmenting the OCB of employees is also discussed. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
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- Date Issued: 2011
Photocatalytic behaviour of tantalum (V) phthalocyanines in the presence of gold nanoparticles towards the oxidation of cyclohexene
- Authors: Chauke, Vongani P , Antunes, Edith M , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247904 , vital:51628 , xlink:href="https://doi.org/10.1016/j.molcata.2010.11.023"
- Description: This paper presents the photocatalytic oxidation of cyclohexene using (OH)3TaPc derivatives in the absence or presence of gold nanoparticles (AuNPs). The photochemical parameters that include photodegradation (ΦP) and singlet oxygen (ΦΔ) quantum yields are also reported in this work. The ΦΔ values were 0.47 and 0.36 for complexes 1a and 1b, respectively. The ΦΔ values improved drastically in the presence of AuNPs to 0.75 and 0.88, respectively. The ΦP values ranged from 1.02 to 2.45 × 10−6, showing stability of TaPc derivatives in the absence and presence of AuNPs. The photocatalytic products identified using gas chromatograph (GC) are cyclohexene oxide, 2-cyclohexen-1-ol, 2-cyclohexene-1-one and 1,2-cyclohexanediol. The percentage conversion values were higher in the presence of AuNPs. Singlet oxygen was determined to be the main agent involved in the photocatalytic oxidation of cyclohexene. The product yield percentage values for both TaPc complexes (1a and 1b) and TaPc in the presence of AuNPs ranged from 6.3 to 21.2%.
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- Date Issued: 2011
Photocatalytic transformation of chlorophenols under homogeneous and heterogeneous conditions using palladium octadodecylthio phthalocyanine
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246816 , vital:51516 , xlink:href="https://doi.org/10.1016/j.molcata.2011.09.003"
- Description: Homogeneous and heterogeneous photosensitized transformations of 4-chlorophenol (4-CP) and pentachlorophenol (PCP) using palladium octadodecylthiophthalocyanine (PdODPc) were investigated. Under heterogeneous conditions, the photosensitizer was supported on functionalized single walled carbon nanotubes (SWCNTs). Homogeneous photosensitization proved to be more effective than the heterogeneous reaction in terms of percentage of transformation achieved. The kinetics of heterogeneous catalysis proved that ads-PdODPc–SWCNT–COOH (where SWCNT has been functionalized with COOH groups) was reusable for 4-CP while its activity degenerated when reused for PCP. Singlet oxygen was confirmed as playing an active role in the reactions.
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- Date Issued: 2011
Photophysical and photochemical behavior of electrospun fibers of a polyurethane polymer chemically linked to lutetium carboxyphenoxy phthalocyanine
- Authors: Zugle, Ruphino , Litwinski, Christian , Torto, Nelson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/248428 , vital:51685 , xlink:href="https://doi.org/10.1039/C1NJ20126C"
- Description: A phthalocyanine complex of lutetium substituted with four peripherally substituted 4-carboxyphenoxy groups was synthesized using cyclotetramerisation reaction. Its structure was elucidated using conventional spectroscopic methods and elemental analysis. The spectral behavior of the complex was studied in DMF solution and in a solid polyurethane fiber matrix. The UV-Visible spectrum showed a red shift in its Q-band maximum absorption within the fiber as compared to that in solution. The triplet quantum yield in DMF was determined to be 0.51 with a lifetime of 2.7 μs and a singlet oxygen quantum yield of 0.33 with a lifetime of 19.85 μs in the same solvent. The functionalized phthalocyanine fiber could be a promising fabric material for applications such as self-disinfecting in wound dressing. A method based on the conversion of ADMA was used to estimate the singlet oxygen quantum yield of the Pc in the hybrid fiber. An estimated singlet oxygen quantum yield value of 0.11 in aqueous medium was obtained. The fluorescence quantum yield of the Pc was found to be 0.01 with a lifetime of 3.20 ns in DMF.
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- Date Issued: 2011
Photophysical behavior of zinc monoaminophthalocyanines linked to mercaptopropionic acid-capped CdTe quantum dots
- Authors: D'Souza, Sarah , Antunes, Edith M , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247634 , vital:51602 , xlink:href="https://doi.org/10.1016/j.jphotochem.2011.03.005"
- Description: Photosensitizing properties of zinc monoaminophthalocyanine (2) {in the absence or presence of mercaptopropionic acid (MPA) capped CdTe quantum dots (QDs)} were compared with those of mono-aminophenoxy zinc phthalocyanine (3), zinc tetrasulfonated phthalocyanine and zinc phthalocyanine. Complexes 2 and 3 were also linked to the MPA capped CdTe quantum dots through the formation of an amide bond. High triplet state quantum yields were obtained for the linked QD–phthalocyanine derivatives (complexes 2 and 3) compared to when complexes 2 and 3 were mixed with MPA QDs without a chemical bond.
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- Date Issued: 2011
Photophysical behaviour of asymmetrically substituted metal free, Mg and Zn phthalocyanines in the presence of folic acid
- Authors: Nombona, Nolwazi , Chidawanyika, Wadzanai J U , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247705 , vital:51608 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.033"
- Description: This work reports on the synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines containing a mono carboxylic acid group for possible linking to biological molecules via an amide bond. Successful synthesis of the phthalocyanines was achieved through the statistical condensation method. The phthalocyanines were mixed with folic acid and their photophysical properties were examined. The triplet quantum yield values for all the complexes in DMSO were between 0.49 and 0.74 and in the presence of folic acid they were between 0.37 and 0.63. The lifetimes were generally good ranging from 70 to 290 μs in the absence or presence of folic acid.
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- Date Issued: 2011
Photophysical characterization of dysprosium, erbium and lutetium phthalocyanines tetrasubstituted with phenoxy groups at non-peripheral positions
- Authors: Zugle, Ruphino , Litwinski, Christian , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247561 , vital:51595 , xlink:href="https://doi.org/10.1016/j.poly.2011.03.030"
- Description: Dysprosium bis-phthalocyanine and monomeric phthalocyanines of erbium and lutetium with non-peripheral phenoxy substituents have been synthesized using two different preparative routes. Photophysical studies on these phthalocyanines revealed that the triplet states of dysprosium and erbium are not populated while the monomeric phthalocyanine complex of lutetium is populated with a quantum yield of 0.83 and a lifetime of 25 μs in DMSO. It was further found that the phthalocyanine complex of lutetium was capable of photochemical generation of singlet state molecular oxygen with yield of 0.71 in THF, thus a promising photosensitizer. However, the three phthalocyanine molecules have very low fluorescence quantum yields of less than 0.01.
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- Date Issued: 2011
Phototransformation of 4-nitrophenol using Pd phthalocyanines supported on single walled carbon nanotubes
- Authors: Ogunbayo, Taofeek B , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247800 , vital:51619 , xlink:href="https://doi.org/10.1016/j.molcata.2011.01.016"
- Description: Adsorption of palladium phthalocyanines complexes on single walled carbon nanotubes was carried out. The resulting composites were employed as catalysts for heterogeneous photocatalytic oxidation of 4-nitrophenol (4-NP) in aqueous media. Singlet oxygen was found to be involved in the phototransformation of 4-NP. Gas chromatographic separation gave hydroquinone and benzoquinone as the phototransformation products. Langmuir–Hinshelwood (L–H) model was employed to evaluate the adsorption and desorption equilibria of the reactants and the products. 2,3,9,10,16,17,23,24-octakis(dodecylthiophthalocyaninato) palladium(II) and 1,4,8,11,15,18,22,25-octakis(dodecylthio phthalocyaninato) palladium, containing the longest alkyl chain gave the best performances.
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- Date Issued: 2011
Porphyrin nanorods modified glassy carbon electrode for the electrocatalysis of dioxygen, methanol and hydrazine
- Authors: George, Reama C , Mugadza, Tawanda , Khene, Samson , Egharevba, Gabriel O , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247388 , vital:51576 , xlink:href="https://doi.org/10.1002/elan.201100081"
- Description: Porphyrin nanorods (PNR) were prepared by ionic self-assembly of two oppositely charged porphyrin molecules consisting of free base meso-tetraphenylsulfonate porphyrin (H4TPPS42−) and meso-tetra(N-methyl-4-pyridyl) porphyrin (MTMePyP4+M=Sn, Mn, In, Co). These consist of H4TPPS42−SnTMePyP4+, H4TPPS42−CoTMePyP4+, H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods. The absorption spectra and transmission electron microscopic (TEM) images of these structures were obtained. These porphyrin nanostructures were used to modify a glassy carbon electrode for the electrocatalytic reduction of oxygen, and the oxidation of hydrazine and methanol at low pH. The cyclic voltammogram of PNR-modified GCE in pH 2 buffer solution has five irreversible processes, two distinct reduction processes and three oxidation processes. The porphyrin nanorods modified GCE produce good responses especially towards oxygen reduction at −0.50 V vs. Ag|AgCl (3 M KCl). The process of electrocatalytic oxidation of methanol using PNR-modified GCE begins at 0.71 V vs. Ag|AgCl (3 M KCl). The electrochemical oxidation of hydrazine began at around 0.36 V on H4TPPS42−SnTMePyP4+ modified GCE. The GCE modified with H4TPPS42−CoTMePyP4+ H4TPPS42−InTMePyP4+ and H4TPPS42−MnTMePyP4+ porphyrin nanorods began oxidizing hydrazine at 0.54 V, 0.59 V and 0.56 V, respectively.
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- Date Issued: 2011
Redox activity of CdTe quantum dots linked to nickel tetraaminophthalocyanine
- Authors: Khene, Samson , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/246457 , vital:51478 , xlink:href="https://doi.org/10.1016/j.microc.2011.06.024"
- Description: Cadmium tellurite quantum dots (CdTe-QDs) are linked to nickel tetraamino phthalocyanine (CdTe-QDs-NiTAPc) through an amide bond. Differential pulse voltammetry shows that that NiTAPc stabilizes the QDs against oxidative disintegration into metallic products on oxidation. Electrocatalytic oxidation of 2, 4-dichlorophenol (DCP) and pentachlorophenol (PCP) on CdTe-QDs and CdTe-QDs-NiTAPc adsorbed or electrodeposited onto a gold electrode were studied. Adsorbed CdTe-QDs-NiTAPc shows the lowest potential for DCP and PCP oxidation and it is also more stable to fouling by PCP and its oxidation products compared to adsorbed CdTe-QDs without NiTAPc. Electrodeposited CdTe-QDs or CdTe-QDs-NiTAPc show the best activity in terms of enhanced currents towards the oxidation of the chlorophenols.
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- Date Issued: 2011
Selection and characterization of suitable lipid excipients for use in the manufacture of didanosine-loaded solid lipid nanoparticles and nanostructured lipid carriers
- Authors: Kasongo, Kasongo W , Pardeike, Jana , Muller, Rainer H , Walker, Roderick B
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/184016 , vital:44156 , xlink:href="https://doi.org/10.1002/jps.22711"
- Description: This research aimed to evaluate the suitability of lipids for the manufacture of solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) loaded with the hydrophilic drug, didanosine (DDI). The crystalline state and polymorphism of lipids with the best‐solubulizing potential for DDI was investigated using differential scanning calorimetry (DSC) and wide‐angle X‐ray scattering (WAXS). DSC and WAXS were also used to determine potential interactions between the bulk lipids and DDI. Precirol® ATO 5 and Transcutol® HP showed the best‐solubilizing potential for DDI. Precirol® ATO 5 exists in the β‐modification before heating; however, a mixture of both α‐ and β‐modifications were detected following heating. Addition of Transcutol® HP to Precirol® ATO 5 changes the polymorphism of the latter from the β‐modification to a form that exhibits coexistence of the α‐ and β‐modifications. DDI exists in a crystalline state when dispersed at 5% (w/w) in Precirol® ATO 5 or in a Precirol® ATO 5/Transcutol® HP mixture. DSC and WAXS profiles of DDI/bulk lipids mixture obtained before and after exposure to heat revealed no interactions between DDI and the lipids. Precirol® ATO 5 and a mixture of Precirol® ATO 5 and Transcutol® HP may be used to manufacture DDI‐loaded SLN and NLC, respectively.
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- Date Issued: 2011
Selective adsorption of PVP on the surface of silver nanoparticles
- Authors: Mdluli, Phumlani S , Sosibo, Ndabenhle M , Mashazi, Philani N , Nyokong, Tebello , Tshikhudo, Robert T , Skepu, Amanda , Van der Lingen, Elma
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247143 , vital:51550 , xlink:href="https://doi.org/10.1016/j.molstruc.2011.07.049"
- Description: The use of surfactants to affect the shape evolution of silver nanoparticles is explored. This allows one to fine-tune the morphological evolution and the optical properties of the metal nanoparticles. Polyvinyl pyrrolidone (PVP) has been used as a surfactant to control the growth of silver nanoparticles at room temperature. In this paper, molecular dynamics simulations were performed to understand regio-selective adsorption of PVP that leads to the preferential growth of silver nanoparticles in dimethylformamide (DMF). The interaction energies between PVP and Ag(1 1 0), Ag(1 0 0) and Ag(1 1 1) crystal planes were calculated and in addition the length density profile of the surfactant on silver surfaces was also examined. Importantly, it has been demonstrated that the length distribution profiles analysis obtained from the molecular dynamics study fully explained the adsorption of PVP on the surface of silver nanoparticles through the carbonyl group of the PVP ring. The application of molecular dynamics simulation technique is important in understanding the evolution of silver nanoparticles and is vital in choosing the right surfactants.
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- Date Issued: 2011
Simulating Collective agency: Joint purpose, presence and power as Constraints to learning in a social Context
- Authors: Kulundu, Injairu
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/386530 , vital:68149 , xlink:href="https://www.ajol.info/index.php/sajee/article/view/122249"
- Description: This paper reflects on the practice of social learning by using my experiences as a social development practitioner in two projects. The first, the Arkwork Collective, is an art-junk process that engages marginalised youth in Grahamstown, South Africa in a process that uses creative sculpture and drama to explore personal and social issues that exist in their immediate context. The second, Jonga Phambili Sinethemba looks into the impact of climate change and HIV/AIDS (amongst other issues) in the rural and peri-urban communities of Willowvale and Lesseyton in the Eastern Cape, South Africa. It seeks to provide a platform where members of each community can define the vulnerabilities, capabilities, social networks in their areas with the aim of bolstering the adaptive capacity of these communities. Snippets of my experiences in these projects are shared with the intention of demonstrating constraints to learning in a social context. Key ideas that the paper explores include honouring the lived experiences of participants as part of the process, prioritising the participation of each individual present as part of the ongoing conversation, the challenge of surfacing the vital independent links of a collective, drawing on the reflective capacity of a diverse group, assessing the quality of participation, building capabilities for ‘response-ability’ and rethinking facilitation. Each section sets out challenges and questions for practitioners in this field to reflect on. The paper suggests that in order to achieve the laudable aims of social learning, we need to peel back the common rhetoric of its participatory aims and acknowledge the complexity, flexibility and dedication that it requires.
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- Date Issued: 2011
Study South Africa
- Authors: International Education Association of South Africa (IEASA) , Jooste, Nico
- Date: 2011
- Subjects: Education, Higher -- South Africa , Universities and colleges -- South Africa , Technical Institutes -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/64952 , vital:28639 , ISBN 9780620512244
- Description: [Extract from article by Ms Merle Hodges]: Over the past year there have been numerous conferences dealing with one general topic. How is it possible for higher education, globally, to produce the same quality in its graduates, research and community outreach when the financial resources entering into the system are radically declining? The conclusion is overwhelmingly despondent. ‘Universities have to do more with less, academics and academic research will increasingly be pressurised by lower salaries internally and career temptations from the corporate world – the impact of which is the greater commodification of universities, and the inevitable decline in academic freedom.’ This global negativity is predicated on inter–related factors. The first, the long tail of the economic recession, is continuing to bite all sectors and higher education is no exception. Secondly, higher education is a little like marketing – when the pressure is on government, sectors like higher education are de–prioritised. In light of this, the position of internationalisation in higher education might seem to fade into the background. Interestingly, the inverse is true. While the zeitgeist of higher education generally appears dismal, the prospects of internationalisation appear rosy in comparison. I believe this is true because of two overlapping issues. Firstly, students are not going to give up on university because of a lingering economic downturn. What they are doing, however, is deciding to travel and study at destinations that would have been perceived as implausible a few years ago. Venezuela, Chile, South Korea and South Africa are all drawing US students more than ever before. This is partly because, I sense, the quality of qualifications is achieving parity across the globe; and also, because students who are prepared to travel realise that cultural specificity – the ability to learn new and unique aspects of a different culture while gaining the same core ingredients of a degree – sets it apart from the degree gained locally. A one semester course in Russian anthropology might appear entirely redundant when applying for a job. However, the very interconnectedness of global business means not only that the course is never a waste of time, but that it might mean the difference between landing a contract and failing to do so. The international student has the benefit of developing in ways that traditional (home-grown) higher education may not yet fully understand. Secondly, development in South Africa at least, has an additional meaning. Our universities are not only focused on developing graduates for multicultural or global competitiveness. Over the past five or so years our universities have been focused on development of the country itself. As an emerging power, the impetus has been on creating universities that address the fundamental needs of the people. Poverty, HIV, sustainability and innovative solutions to global problems are the very sap of South African universities in the 21st Century. How to create a sustainable environment, how to preserve marine and wildlife, how to create jobs, reduce poverty, and maximise innovation – these are the concerns that are preoccupying the minds of the country’s best academics. , 11th Edition
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- Date Issued: 2011
Syntheses and electrochemical characterization of new water soluble octaarylthiosubstituted manganese phthalocyanines
- Authors: Booysen, Irvin N , Matemadombo, Fungisai , Durmus, Mahmut , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247614 , vital:51600 , xlink:href="https://doi.org/10.1016/j.dyepig.2010.09.012"
- Description: This paper reports on the synthesis and characterization of new manganese phthalocyanine (MnPc) complexes: 2,3-octakis-[(2-mercaptopyridine) phthalocyaninato] acetato manganese (III) (1) and its quaternized (hence water soluble) derivative: 2,3-octakis-{[(N-methyl-2-mercaptopyridine) phthalocyaninato] acetato manganese (III)} sulphate (2). The complexes were used to form self assembled monolayers (SAMs). Voltammetry proved that both of the SAMs are well packed, strongly passivating and act as selective and efficient barriers to ion permeability. Furthermore, surface coverage studies confirmed that the MPc macrocycles adsorb onto the gold electrode as monolayers. Both MPc SAMs were successfully used as electrochemical sensors of nitrite.
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- Date Issued: 2011
Syntheses, electrochemical and spectroelectrochemical properties of novel ball-type and mononuclear Co (II) phthalocyanines substituted at the peripheral and non-peripheral positions with binaphthol groups
- Authors: Canlıca, Mevlüde , Booysen, Irvin Noel , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247837 , vital:51622 , xlink:href="https://doi.org/10.1016/j.poly.2010.11.017"
- Description: Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1′-binaphthyl-8,8′-diol and ball-type dinuclear Co2Pc2 substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1′-binaphthol-bridges were prepared from the corresponding phthalonitriles 4–7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(CoIPc−2)2]2−/[(CoIPc−3)2]4− (I), (CoIIPc−2)2/[(CoIPc−2)2]2− (II) and one oxidation process assigned to [(CoIIIPc−2)2]2+/CoIIPc−2)2 (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.
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- Date Issued: 2011
Synthesis and electrocatalytic behavior of cobalt (II)-tris (benzyl-mercapto)-monoaminophthalocyanine–single walled carbon nanotube nanorods
- Authors: Mugadza, Tawanda , Nyokong, Tebello
- Date: 2011
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/247882 , vital:51626 , xlink:href="https://doi.org/10.1016/j.electacta.2010.11.016"
- Description: In this paper we report on synthesis and electrocatalytic behavior of cobalt (II)-tris(benzyl-mercapto)-monoaminophthalocyanine–single walled carbon nanotube nanorods towards the oxidation of amitrole. SWCNTs that were terminally functionalized with carboxylic acid groups were chemically linked to cobalt (II)-tris(benzyl-mercapto) monoaminophthalocyanine (CoMAPc) via an amide bond to form nanorods. UV–vis, FTIR, TEM, Raman and XRD spectroscopies were used in characterization of the nanorods (CoMAPc–SWCNT-linked), while cyclic voltammetry and chronoamperometry were used during the characterization of amitrole on the modified glassy carbon electrode. The linear dynamic range for the amitrole was from 1.0 × 10−6 M to 1.2 × 10−4 M, with a sensitivity of 6.76 A mol−1 L cm−2. The estimated limit of detection for amitrole was 0.10 μM, using the 3δ criterion. The catalytic rate constant was found to be 1.09 × 105 M−1 s−1.
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- Date Issued: 2011